The red and white color of the eastern tropical Pacific in the upper image (from Nov. 1997) indicates higher than normal ocean level due to piling up of warm ocean water during El Nino. The lower image (Feb 1999) shows ocean level during La Nina when there is cool water from upwelling in the eastern tropical Pacific. These maps use data from TOPEX/POSEIDON and Jason 1 to show the height of the ocean surface. Courtesy of NASA/JPL